Redstone dust on top of (or below) a redstone block will not power the blocks immediately adjacent to the dust unless those blocks contain more redstone dust

I was trying to make the BUD tnt in MCPE and I found something weird.
When I updated the tnt, it did not blow up. I then made the redstone dust on the redstone block point towards the tnt. It STILL didn't blow up. Then I connected a lever to the redstone dust and turned it on even though the redstone appeared to be 'powered'. The tnt then blew up.